According with the aging of the population, dementia have been a dominant disease in the medication of the elderly patients. However, the remedies for the treatment of dementia have not been established. Cerebral metabolism enhancers, cerebral blood flow improving agents, tranquilizers. cholinomimetic agents and the like have been tried to use for the treatment. However, the effect of these agents are not reproducible and insufficient. Therefore, better remedies for treatment have been required.
In the dementia of alzheimer type, a type of senile dementia, various nervous systems are damaged. Especially, it has been reported that cholinergic nervous systems, which play important roles in learning and memory functions, are significantly damaged. Therefore, the development of central acethylcholinergic neuron enhancers have been an large stream of development in the improving agents for learning and memory disorders. As for the acethylcholinergic neuron enhancers, precursors (such as choline and lecithin), choline esterase inhibitors or muscarinic agonists have been developed so far. However, they are not satisfactory enough.
On the other hand, various kinds of pyrimidine derivatives have been reported.(for example, CA 93:45871w, 97:158036d, 98:34562y, 100:209733u, 101:110856v, 102:162193s, 104:47176t, 107:236641p, 109:92924z and so forth). It is described in CA 100:209733u that the phleomycin amplifying effect of the compounds which have similar structures to the compounds of the present invention. Also in CA 104:47176t, it is described that the plant's growth regulating effect of the compounds which have similar structures to the compounds of the present invention.
However, up to this point, there have been no literatures describing that the compounds of the present invention and analogous pyrimidine derivatives have improving effects on learning and memory disoders.